Vazifa 1 . 1+2*1/3+3(1/3) 2 +…+100(1/3) 99 yig‘indisini toping ;
Yechim.
g ( x )=1+2 x +3 x 2 +…+100 x 99 yig'indisini toping va unga x = 1/3 ni qo'ying .
f ( x )= x + x 2 +…+ x 100 yordamchi funksiya kerak bo'ladi .
f '( x )= g ( x ) ekanligi aniq .
f ( x ) - geometrik progressiyaning yig'indisi.
f ( x )=( x - x 101 )/(1 - x ) ekanligini hisoblash oson . Ma'nosi,
g ( x ) = f '( x ) = ((1-101 x 100 )(1- x )-( x - x 100 )(-1))/(1- x ) 2 =(1-102 x 100 +101 x 101 )(1- x ) 2 .
X = 1/3 ni almashtiring .
Javob: 0,25 (9-205 * 3 -99 )
Vazifa 2018-03-22 _ 1+2*3+3*3 2 +…+100*3 99 yig‘indisini toping ;
Yechim.
g ( x )=1+2 x +3 x 2 +…+100 x 99 yig'indisini toping va unga x = 1/3 ni qo'ying .
f ( x )= x + x 2 +…+ x 100 yordamchi funksiya kerak bo'ladi .
f '( x )= g ( x ) ekanligi aniq .
f ( x ) - geometrik progressiyaning yig'indisi.
f ( x )=( x - x 101 )/(1 - x ) ekanligini hisoblash oson . Ma'nosi,
g ( x ) = f '( x ) = ((1-101 x 100 )(1- x )-( x - x 100 )(-1))/(1- x ) 2 =(1-102 x 100 +101 x 101 )(1- x ) 2 .
X = 3 ni almashtiring .
Javob: ≈ 2,078176333426855507665737416578*10 50 .
3 -topshiriq . M (4;3) nuqtadan y = (9- x 2 )/6 grafigiga chizilgan tangenslarning OX o'qi bilan A va B kesishish nuqtalari bo'lsa , AMB uchburchakning maydonini toping .
Yechim.
t.A = y cas1 ∩ OX Yechim :
t.B = y cas2 ∩ OX y cas = y ( x 0 ) +y'( x 0 )( x - x 0 ) ;
y \u003d (9 - x 2 ) / 6 y '(x 0 ) \u003d -2x * 1/6 \u003d -x / 3;
M (4;3)________ chunki y cas M (4;3) dan o'tadi , keyin
S AMB -? 3 \u003d (9 - x 0 2 ) - (4 - x 0 ) * x 0/3 | *3
18 \u003d 9-x 0 2 -2x 0 (4-x 0 ) ;
x 0 2 -8 x 0 -9 \u003d 0 ;
D / 4 \u003d 16 + 9 ;
x 0 \u003d 4 + 5 \u003d 9 ;
x 0 \u003d 4-5 \u003d -1
da cas1 \ u003d -12 - ( x -9) * 9/3 \u003d -3 x +15 ;
y cas1 = 4/3 + ( x +1) * 1/3 = x / 3 + 5/3 ;
A(5;0); B (-5;0);
AM = √10 ( birlik );
AB = 10 ( birlik );
BM = 3√10 ( birlik );
p - perimetri bo'ylab ; __
p = (4√10 + 10)/2 = 2√10 + 5 ;
__ __ __ __ __ __
S = √ ( 2√ 10 + 5 ) (2 √ 10 + 5 - √ 10 ) ( 2 √ 10 + 5 - 3 √ 10) (2 √ 10 + 5 - 10 ) =
= √ (2√10 + 5)(√10 + 5)(5-3√10)(2√10-5) =
\u003d √ (40-25) (25-10) \u003d 15 (ed 2 );
Javob: 15 ( 2 -birlik ) .
4-topshiriq . OAB uchburchagining OA va OB tomonlari y = (| x | - x )/2 funksiya grafigida yotsa va AB toʻgʻrisi M (0;1) nuqtadan oʻtsa , eng kichik tekislik qanday boʻlishi mumkin .
Yechim:
- x , x <0
y=
0, x>0
A(a;-a); B (b;0);_
AO = |a|√2 = -a√2 ( t . dan . a<0);
BO = b ;
V. V uchun :
y 1 = kx + z ;
chunki y 1 - m M (0; 1) dan o'tuvchi chiziqli proportsionallik grafigi , keyin z = 1 .
0=kx+1 ;
k=-1/b ;
A nuqtasi uchun :
y 1 \ u003d kx +1 ;
-a=kx+1 ;
k=(-1-1a)/a ;
y 1A = y 1B
(-a-a)/a = -1/b ;
b+ab=a ;
a(1-b)=b ;
a = b/(1-b) ;
S ∆AOB =0,5*AO*OB*sin / _AOB
AOB \u003d 180 o - 45 o \u003d 13 5 o
S ∆AOB =0,5*(√2/2)* (-a)b√2 = -ab/2 ;
S ∆AOB \u003d -b 2 / (2 (1 - b)) \u003d b 2 / (2 (1 - b)) ; D(y): b> 1 ( chunki b < 1 emas ∆AOB shakllari .) ;
chunki funktsiya uzluksiz va b > 1 da differentsial bo'ladi , keyin uning hosilasini topaman:
S' = (4b(b-1)-b 2 )/(4(b-1) 2 ) = (4b 2 -4b-2b 2 )/(4(b-1) 2 ) = 2b(b-2) )/(4(b—1) 2 ) =
= b(b-2)/(2(b-1) 2 ) ;
S ' = 0 ;
ekstremal nuqtalar:
b=0 ;
b=1 ;
b=2 ;
lekin b > 1 , shuning uchun
S naim \ u003d S (2) \u003d 4 / (2 (2-1)) \u003d 2 (ed 2 ) ;
Javob: 2 birlik 2 .
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